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Project

Dietary TRPM8 ligands in inflammation-triggered gut diseases

Diet has a central role in the normal gut microenvironment, impacting microbial composition, function, gut barrier and host immunity. Alterations in single food groups have far ranging implications, including the pathogenesis of inflammatory bowel diseases (IBD). IBDs are characterized by chronic inflammation of the digestive tract, which causes an abnormal production of growth cytokines and metabolic free radicals. Anti-inflammatory and immunosuppressive drugs (i.e. immunosuppressants, corticosteroids, aminosalicylates, and biotherapy agents) are currently used for IBD treatment. However, these therapies are not resolutive nor prophylactic and can cause severe adverse effects, which include immunodepression and enhanced susceptibility to various malignancies. Based on this background, nutraceuticals play an increasingly key role, both for prevention therapies, and for curative therapies alongside with traditional drugs, with the benefit of not having almost any side effects. TRPM8 is a member within the subset of temperature-sensitive TRP channels and it is the main receptor involved in cold sensation. Of note, many of reported TRPM8 agonists and blockers are food-derived molecules, and some of them have proven a promising pharmacological activity: (i) menthol (from Mentha x piperita) and eucalyptol (from Eucalyptus spp.) are TRPM8 agonists; (ii) sesamin (from Sesamum indicum) is a TRPM8 blocker. Interestingly, it has been recently reported an involvement of TRPM8 in gut disorders, and in particular in the innate immunity responses. Furthermore, peppermint oil-based preparations are already used by patients with irritable bowel syndrome because of their analgesic, antispasmodic, and carminative effects. Hence, considering that the knowledge of TRPM8 role in IBD is still greatly fragmentary, and the effect of its agonists or antagonists is often contradictory concerning chronic inflammation, the aims of this project are: 1) to identify new TRPM8 dietary occurring ligands by molecular docking and intracellular calcium assay (on TRPM8 overexpressing transfected cells); 2) to deepen the implication of TRPM8 in IBDs, evaluating the effect of the most promising ligands in intestinal models of inflammation in vitro, in vivo, and ex vivo. The first part of this project was conducted at the University Federico II under the supervision of Professor Angelo A. Izzo and Professor Raffaele Capasso, and led to the identification of luteolin as a new and selective dietary TRPM8 antagonist (IC50 3.006 μM). Therefore, we have shown that luteolin significantly reduces the release of pro-inflammatory mediators (i.e. NO2-, IL-1b, IL-6, TNF-a) in M1 wild type (WT) bone marrow derived macrophages (BMDMs), but not in M1 Trpm8-/- BMDMs, suggesting a TRPM8 mediated antiinflammatory effect. Moreover, it’s emerged that TRPM8 deletion itself significantly reduces the release of pro-inflammatory mediators by stimulated M1 macrophages. Hence, with the group of the Laboratory of Mucosal Immunology at KU Leuven, under the supervision of Professor Gianluca Matteoli, we will further elucidate the role of TRPM8 in IBDs, analyzing its expression in human biopsies and peripheral blood mononuclear cells of patients with IBDs compared to healthy controls. Using BMDMs from WT and Cre-Lox recombinant mice, we will be able to analyze via RNA sequencing, if the blockade or the absence of TRPM8 receptor is correlated to differences in genetic pathways involved in IBD pathogenesis. Finally, we will perform an in vivo model of chronic colitis induced by dextran sodium sulphate (DSS) in WT and Trpm8 global or conditional knock-out mice, treated or not with luteolin, to evaluate possible alterations in the immune response following the treatment with luteolin, and if its already reported anti-inflammatory effect is TRPM8 mediated.

Date:14 Feb 2023 →  Today
Keywords:Inflammatory Bowel Diseases, Nutraceuticals, TRPM8
Disciplines:Inflammation, Innate immunity
Project type:PhD project